1. Field of the Invention
The present invention relates to a method of generating a data linkage program for linking data among a plurality of computer systems and more particularly to a method of generating a data linkage program suited for use in a data linkage system that performs data transfers among a plurality of computer systems via storage devices.
2. Description of the Related Art
Many corporations today store transaction data, including daily operations information, in operational databases in their head offices. The operational databases are mostly run on mainframe-based systems. Analytical systems that analyze daily operational data sources to support decision making functions are often run on open systems.
Normally, analytical systems need to reference operational databases. However, the operational databases in general include data items not used by the analytical systems and the data items used for analysis vary depending on what is to be analyzed. For this reason, a data linkage system is often used to generate a database in an open system for the analytical system to access. The data linkage system has a function of extracting only necessary data from the mainframe database, processing the extracted data as required and storing it in the database in the open system.
An example of the data linkage system is disclosed in JP-A-2001-22715. The method described in this official gazette to build a data linkage system involves connecting a mainframe and an open system to a disk subsystem, one form of a storage device, and performing data transfers within the disk subsystem.
FIG. 2 shows a configuration of the data linkage system which comprises a mainframe 101, an open system 102 and a disk subsystem 103. The disk subsystem 103 has a mainframe volume 108, an open system volume 110 and a shared volume 109. The shared volume 109 is a storage area in which data is shared by the mainframe 101 and the open system 102. Data to be shared are stored in intermediate files 105 generated in the shared volume 109. The intermediate files 105 can be produced only by an intermediate file area securing program 201 in the mainframe 101.
A procedure for transferring data from a mainframe database 104 to an open system database 106 and storing the data there is taken as an example. The intermediate file area securing program 201 generates an intermediate file 105. Next, a data linkage program 202 in the mainframe 101 writes data from the mainframe database 104 into the intermediate file 105. Then, a data linkage program 203 on the open system 102 reads the data written in the intermediate file 105 and writes it into the open system database 106. Transferring data from the open system database 106 to the mainframe database 104 is done by reversing the procedure described above.
In the conventional technique described above, to transfer data from the mainframe database 104 via the intermediate file 105 to the open system database 106, needs three programs: (1) the data linkage program 202 run by the mainframe 101, (2) the intermediate file area securing program 201 and (3) the data linkage program 203 run by the open system 102. There is a wide range of Items to be analyzed by the analytical system and data items to be extracted from the mainframe database also vary according to what target item is to be analyzed. Thus, the above conventional technique must generate a data linkage program for each analysis item.
Further, since a format of the intermediate file to be generated varies depending on the kind and the number of data items to be extracted, the intermediate file area securing program must also be created for each analysis item.
Moreover, the above three programs need to be executed sequentially to operate as a system. These programs, however, are independent of each other and there is no link among them.
As described above, the conventional method has drawbacks that to build a data linkage system for linking the mainframe with the open system requires creating the three programs for each different purpose and that since they are independent of each other, there is no link between them.
It is an object of the present invention to provide a method of creating programs required by a data linkage system and linking a plurality of different systems together.